1. Field of the Invention
The invention relates to a method and apparatus for continuously monitoring the blood pressure of patients under hospital, or other conditions. More specifically, the invention relates to such a method and apparatus for continuously monitoring systolic blood pressure by detecting variables proportional to blood pressure.
2. Description of the Prior Art
An interesting and informative survey of methods for measuring blood pressure is given in a book by L. A. Geddes published by the Yearbook Medical Publishers, Inc., Chicago, 1970, entitled "The Direct and Indirect Measurement Of Blood Pressure". The method include direct method with a transducer outside the artery, as discussed by T. E. Piemme in his article in Progress In Cardiovascular Diseases, 5, (1963), p. 574 in an article entitled " Pressure Measurements: Electrical Pressure Transucer"; a direct method with the transducer inside the artery, which is discussed by H. P. Pieper in the Journal of Applied Physiology, 22, February 1967, in an article entitled "Catheter Tip Manometer for Measuring Blood Pressure During Changes"; and the well known indirect occlusive method wherein an inflatable cuff is wrapped around the arm. The last mentioned method is commonly used by doctors in their offices as well as during examinations in the hospital.
The first two methods require the puncturing of an arterty, and the last method cannot be used for continuously monitoring blood pressure over long periods of time as the cuff must be inflated each time a reading is to be taken.